Industrial asphalt composition

ABSTRACT

This invention is based upon the discovery that a small amount of lime can be incorporated into industrial asphalt to greatly improve its resistance to oxidative hardening cracking and low temperature thermal cracking. The incorporation of a small amount of lime into industrial asphalt accordingly results in products made therewith offering improved service life. For instance, roofing shingles made with such asphalt that contains a small amount of lime will be more resistant to cracking and failure in both hot and cold weather climates. The subject invention more specifically discloses an asphalt roofing shingle having an upper surface and an underside, said asphalt roofing shingle being comprised of a fiber mat which is coated with an asphalt composition, wherein the upper surface of the asphalt roofing shingle includes a layer of roofing granules, wherein the asphalt composition has a softening point which is within the range of 185° F. (85° C.) to 250° F. (121° C.) and a penetration value of at least 15 dmm, and wherein the asphalt composition contains from 0.1 weight percent to 5 weight percent lime. The subject invention further discloses a method for preparing an industrial asphalt comprising (1) heating a base asphalt to a temperature which is within the range of about 100° F. (38° C.) to 400° F. (204° C.) to produce a hot base asphalt, and (2) mixing from 0.1 weight percent to 5 weight percent lime throughout the hot base asphalt while the mixture of hot base asphalt and lime is maintained at a temperature which is within the range of 100° F. (38° C.) to 400° F. (204° C.) to produce the industrial asphalt.

FIELD OF THE INVENTION

The present invention relates to asphaltic materials which areparticularly useful in manufacturing industrial asphalt products such asroofing shingles, roll roofing membranes, roofing underlayment,asphalt-based adhesives, asphalt-based sealants and built-up roofing.The present invention also relates to a method for preparing suchasphaltic materials.

BACKGROUND OF THE INVENTION

Asphalt offers outstanding binding and waterproofing characteristics.These physical attributes of asphalt have led to its widespreadutilization in paving, roofing, and waterproofing applications. However,with exposure to elements of the environment such as solar radiation,high temperatures, rain, snow, etc., the asphalt ages as a result ofoxidation. With oxidation, asphalt becomes stiffer, less ductile, andless capable of relieving stress. When the stress in the asphalt buildsto a critical limit in excess of what it can withstand, cracking occurs.This type of cracking which is caused mainly by asphalt oxidation oraging is called “oxidative hardening cracking.” This type of cracking istypical and commonly experienced in the Sun Belt where asphalt can beexposed to a grueling sun and high temperatures for an extended periodof time.

Exposure to low temperatures can also cause asphalt to crack. Asphalt isa viscoelastic material, meaning it behaves more like a solid at lowtemperatures and behaves as a liquid at high temperatures. As a result,with drops in temperature, asphalt's viscosity and modulus can increasesignificantly. In addition, asphalt has a relatively high coefficient ofthermal expansion (CTE), and under most conditions, asphalt's CTE ishigher than the substrate to which it is applied (such as wood ormetal). With considerable temperature drops, asphalt will experiencemuch more contraction than its substrate. However, the substrate keepsthe asphalt from contracting freely, and as a result, stress is builtinside of the asphalt. When the stress built in asphalt exceeds thecritical value that it can withstand, cracking occurs. Cracking causedby low temperature is called “low temperature thermal cracking”. Thisform of cracking mainly occurs in cold climates, such as in the northernUnited States and Canada during the winter.

Each year asphalt cracking costs various industries billions of dollars.As a result, it is desirable to have a method to improve the durabilityand service life of asphaltic materials. To improve asphalt resistanceto “oxidative hardening cracking” asphalt has to be modified to be lesssusceptible to oxidative hardening. To improve asphalt resistance to“low temperature thermal cracking” asphalt has to have better lowtemperature flexibility.

Hydrated lime, Ca(OH)₂, is commonly used in the paving industry as ananti-strip agent to treat aggregate. It is believed that hydrated limeis able to improve asphalt-aggregate interaction (or bonding) to reducemoisture/water damage to asphalt pavement. In this technology, a smallamount of dry hydrated lime is blended with the aggregate for a certaintime period and then the treated aggregate is mixed with hot asphalt toproduce a hot asphalt/aggregate mixture. U.S. Pat. No. 5,512,093discloses a process to treat aggregate with a quicklime slurry. In thisprocess the properties of hot mix asphalt are improved by treating theaggregate which is combined with bituminous binder and lime. A hotquicklime slurry is produced by slaking quicklime with water at the siteof the hot mix asphalt plant using a portable mixing tank. The hotquicklime slurry is then applied to the aggregate. The aggregate isdried and combined with the binder to produce the hot mix asphalt.

U.S. Pat. No. 6,027,558 discloses a hot mix asphalt composition in whichhydrated lime is added directly to the asphalt binder prior to theaddition of the asphalt binder to the mineral aggregate constituent ofthe composition. The lime-asphalt mixture is then added to the mineralaggregate. The lime component is added to the asphalt binder in anamount which exceeds about 10% by weight, based upon the total weight ofasphalt binder in the composition. U.S. Pat. No. 6,027,558 alsodiscloses an improved hot mix asphalt paving composition, comprising: alime-asphalt mixture and mineral aggregate, the lime-asphalt mixturebeing first formed by adding a lime component directly to an asphaltbinder prior to addition of the asphalt binder to the mineral aggregatematerial; and wherein the lime component is present in the lime-asphaltmixture in an amount which exceeds about 10% by weight, based upon thetotal weight of asphalt binder.

When a relatively high level of hydrated lime (for instance, greaterthan about 10%) is added to asphalt, the hydrated lime will typicallyact mainly as filler. In such cases, the improvements observed comemainly from physical asphalt-hydrated lime interactions. High levels oflime have been incorporated into paving asphalt compositions for decadesas an antistripping agent.

U.S. Pat. No. 6,562,118 discloses a method for the modification ofasphaltic compositions such that cellulosic fibers are not degraded bythe asphalt at elevated temperatures. This is achieved by the additionof certain inorganic or organic alkaline materials to the composition.The alkaline materials that can be used are selected from the groupconsisting of hydroxide, carbonates, silicates and basic salts of GroupI, II and III metals and suitable organic bases which arethermodynamically stable under the conditions that the asphaltcomposition will be used.

SUMMARY OF THE INVENTION

This invention is based upon the discovery that a small amount of limecan be incorporated into industrial asphalt to greatly improve itsresistance to oxidative hardening cracking and low temperature thermalcracking. The incorporation of a small amount of lime into industrialasphalt accordingly results in products made therewith offering improvedservice life. For instance, roofing shingles made with such asphalt thatcontains a small amount of lime will be more resistant to cracking andfailure in both hot and cold weather climates.

In this application, a relatively low amount (0.1 to 5% by weight basedupon the weight of asphalt) of lime, preferably hydrated lime, is addedto the industrial asphalt to attain improved properties. Thisimprovement is believed to be a result of the chemical interactionbetween the asphalt and the lime. In any case, industrial asphaltproducts such as roofing shingles, roll roofing membranes, roofingunderlayment, asphalt-based adhesives, asphalt-based sealants andbuilt-up roofing made with such lime treated asphalt offer improvedservice life under adverse environmental conditions.

The subject invention more specifically discloses an asphalt roofingshingle having an upper surface and an underside, said asphalt roofingshingle being comprised of a fiber mat which is coated with an asphaltcomposition, wherein the upper surface of the asphalt roofing shingleincludes a layer of roofing granules, wherein the asphalt compositionhas a softening point which is within the range of 185° F. (85° C.) to250° F. (121° C.) and a penetration value of at least 15 dmm, andwherein the asphalt composition contains from 0.1 weight percent to 5weight percent lime.

The subject invention also reveals an asphalt roll roofing membrane thatis comprised of a reinforcing mat having an upper side and a lower sidewherein said reinforcing mat is coated on its upper surface and itslower surface with an asphalt composition that is comprised of asphaltand from 0.1 weight percent to 5 weight percent lime.

The subject invention also reveals a roofing underlayment which iscomprised of an asphalt saturated roofing paper or an asphalt saturatedglass fiber mat wherein the asphalt contains from 0.1 weight percent to5 weight percent lime.

The present invention further discloses a built-up roofing which iscomprised of multiple layers of roofing paper or felt that are adheredtogether with asphalt and which is covered on its upper surface withmineral roofing granules or gravel wherein the asphalt contains from 0.1to 5 weight percent lime.

The present invention further discloses an adhesive composition which iscomprised of asphalt and of a block copolymer modifier wherein theasphalt contains from 0.1 to 5 weight percent lime.

The subject invention further discloses a method for preparing anindustrial asphalt comprising (1) heating a base asphalt to atemperature which is within the range of about 100° F. (38° C.) to 400°F. (204° C.) to produce a hot base asphalt, and (2) mixing from 0.1weight percent to 5 weight percent lime throughout the hot base asphaltwhile the mixture of hot base asphalt and lime is maintained at atemperature which is within the range of 100° F. (38° C.) to 400° F.(204° C.) to produce the industrial asphalt.

The present invention also reveals an industrial asphalt compositioncomprising asphalt and from 0.1 weight percent to 5 weight percent lime,wherein the asphalt has a softening point which is within the range of185° F. (85° C.) to 250° F. (121° C.), wherein the asphalt has apenetration value of at least 15 dmm, and wherein the asphaltcomposition is void of aggregate, such as small stones and crushedrocks.

DETAILED DESCRIPTION OF THE INVENTION

The process of this invention is useful in treating asphalt to produceindustrial asphalt with improved durability. Such industrial asphalt canbe used in making articles of manufacture having improved resistance tocracking at both low and high temperatures. Articles made with theimproved industrial asphalt of this invention are typically moreresistant to deterioration and provide a longer useful service life. Theimproved industrial asphalt made by the technique of this invention isparticularly useful in manufacturing asphalt roofing products, such asasphalt roofing shingles. Roofing shingles made with the industrialasphalt of this invention offer a higher level of resistance to crackingand deterioration than do roofing shingles made with conventionalasphalt. This advantage is of particular importance in cases whereroofing shingles will be used on buildings that are located ingeographic regions that experience extremely hot and/or cold weatherconditions. In any case, roofing shingles made with the improvedindustrial asphalt of this invention normally provide a longer usefulservice life.

The technique of this invention can be used to improve the crackresistance of virtually any industrial asphalt. The base asphalt treatedby the process of this invention is normally the petroleum residue froma vacuum distillation column used in refining crude oil. The asphalticmaterial used as the starting material can also be air blown asphalt,solvent extracted asphalt, naturally occurring asphalt, or syntheticasphalt. Blends of such asphaltic materials can also be treated by theprocess of this invention. The asphalt flux can also include polymers,recycled tire rubber, recycled engine oil residue, recycled plastics,softeners, antifungal agents, biocides (algae inhibiting agents), andother additives. Tar and pitch can also be used as the starting materialfor treatment by the technique of this invention.

The industrial asphalt that is used in manufacturing roofing shingleswill normally have a softening point which is within the range of 185°F. (85° C.) to 250° F. (121° C.) and a penetration value of at least 15dmm. Preferably, industrial asphalt that is used in making roofingshingles will have a softening point which is within the range of 185°F. (85° C.) to 235° F. (113° C.), and a penetration value which iswithin the range of 15 dmm to 35 dmm. Finally, industrial asphaltemployed in manufacturing roofing shingles will more preferably have asoftening point which is within the range of 190° F. (88° C.) to 220° F.(104° C.) and a penetration value which is within the range of 15 dmm to25 dmm.

For purposes of this invention, asphalt softening points are measuredfollowing ASTM D 36-95 “Standard Test Method for Softening Point ofBitumen (Ring-and Ball Apparatus)” and asphalt penetrations are measuredfollowing ASTM D 5-97 “Standard Test Method for Penetration ofBituminous Materials”.

In other embodiments of this invention the asphalt can be (1) a Type Iasphalt which has a softening point of from 135° F. (57° C.) to 151° F.(66° C.) and a penetration of from 18 dmm to 60 dmm at 77° F. (25° C.),(2) a Type II asphalt which has a softening point of from 158° F. (70°C.) to 176° F. (80° C.) and a penetration of from 18 dmm to 40 dmm at77° F. (25° C.), (3) a Type III asphalt which has a softening point offrom 185° F. (85° C.) to 205° F. (96° C.) and a penetration of from 15dmm to 35 dmm at 77° F. (25° C.), or (4) a Type IV asphalt which has asoftening point of from 210° F. (99° C.) to 225° F. (107° C.) and apenetration of from 12 dmm to 25 dmm at 77° F. (25° C.).

The asphalt treated by the technique of this invention can be air blownto attain the desired softening point. In such an air blowing procedurethe asphalt is heated to a temperature which is within the range of 400°F. (204° C.) to 550° F. (288° C.) and an oxygen containing gas is blown(sparged) through it. This air blowing step will preferably be conductedat a temperature which is within the range of 425° F. (218° C.) to 525°F. (274° C.) and will most preferably be conducted at a temperaturewhich is within the range of 450° F. (232° C.) to 500° F. (260° C.).This air blowing step will typically take about 2 hours to about 8 hoursand will more typically take about 3 hours to about 6 hours. However,the air blowing step will be conducted for a period of time that issufficient to attain the ultimate desired softening point andpenetration value. In making industrial asphalt for roofing shingles theasphalt will typically be air blown until a softening point which iswithin the range of 185° F. (85° C.) to 250° F. (121° C.) and apenetration value of at least 15 dmm is attained.

The oxygen containing gas (oxidizing gas) used in such an air blowingstep is typically air. The air can contain moisture and can optionallybe enriched to contain a higher level of oxygen. Chlorine enriched airor pure oxygen can also be utilized in the air blowing step. Air blowcan be performed either with or without a conventional air blowingcatalyst. Some representative examples of air blowing catalysts includeferric chloride (FeCl₃), phosphorous pentoxide (P₂O₅), aluminum chloride(AlCl₃), boric acid (H₃BO₃), copper sulfate (CuSO₄), zinc chloride(ZnCl₂), phosphorous sesquesulfide (P₄S₃), phosphorous pentasulfide(P₂S₅), phytic acid (C₆H₆[OPO—(OH)₂]₆), and organic sulfonic acids.

The asphalt treatment process of this invention is conducted by firstheating the asphalt being treated to a temperature which is within therange of about 100° F. (38° C.) to 400° F. (204° C.) to produce a hotbase asphalt. Then from about 0.1 weight percent to about 5 weightpercent lime, preferably hydrated lime, is mixed throughout the hot baseasphalt while it is maintained at a temperature which is within therange of 100° F. (38° C.) to 400° F. (204° C.) to produce the industrialasphalt. In most cases this mixing step will be conducted over a timeperiod which is within the range of about 10 minutes to about 4 hours.The lime will typically be mixed into the asphalt over a period of about20 minutes to 2 hours. Typically about 0.5 weight percent to about 4weight percent of the lime will be added to the hot base asphalt. It isgenerally preferred to mix 1 weight percent to 3 weight percent of thelime into the base asphalt.

For purposed of this invention “lime” refers to compounds that includeat least one of following functional components: (1) quicklime (CaO);(2) calcium hydroxide (Ca(OH)₂); (3) dolomitic quicklime (CaO.MgO); (4)dolomitic normal hydrate (Ca(OH)₂.MgO); (5) dolomitic pressure hydrate(Ca(OH)₂.Mg(OH)₂); and (6) mixtures of any or all of these functionalcomponents. It is preferred for the lime to be hydrated lime.

In the practice of this invention it may be advantageous to add the limeto the base asphalt at the end of the air blow procedure while the blownasphalt is still hot. By adding the lime to the hot asphalt at the endof the air blowing step it is not necessary to heat the asphalt fromambient temperature to the required mixing temperature. This can saveenergy because the lime is added to the base asphalt after it is beingcooled from the temperature used in the air blowing procedure. The limecan optionally be mixed into the base asphalt in the vessel used for theair blowing in which case agitation can be provided by continuing toblow air or some other gas into the asphalt being treated tohomogeneously disperse the lime through it. After the lime is dispersedthroughout the asphalt it is, of course, cooled to ambient temperatureto produce the improved industrial asphalt of this invention.

The improved industrial asphalt of this invention can be used in makingroofing products and other industrial products using standardprocedures. For instance, the industrial asphalt can be blended withfillers (such as, limestone, stonedust, sand, mica, slate flour,diatorriaceous earth and the like), stabilizers, polymers, recycled tirerubber, recycled engine oil residue, recycled plastics, softeners,antifungal agents, biocides (algae inhibiting agents), and otheradditives. The filler can optionally be a glass filler, such as choppedglass fibers.

Asphalt roofing shingles can be made by coating a fiber mat with theimproved industrial asphalt composition of this invention andsubsequently applying a layer of roofing granules to the upper surfacethereof to produce the roofing shingle. This is normally accomplished by(1) unwinding a roll of fiber roofing mat, (2) coating the fiber roofingmat with the industrial asphalt of this invention which has been heatedto an elevated temperature while the fiber roofing mat is being unwound,(3) applying mineral roofing granules to the asphalt-covered surface ofthe mat and embedding the granules in the hot asphalt to form asingle-layer sheet of shingle material, (4) cooling the sheet of shinglematerial to ambient temperature, and (5) cutting the sheet of shinglematerial into roofing shingles of the desired size and shape.

The fiber roofing mat will typically be comprised of an inorganic fiber,such as a glass fiber. For instance, the fiber roofing mat can becomprised of a polysiloxane compound having —[SiO]— repeating units.However, the fiber roofing mat can optionally be comprised of one ormore organic polymeric fibers, such as polyethylene, polypropylene,polyester, nylon, or acrylic fibers. On the other hand, the fiberroofing mat can be void of organic fibers, such as cellulosic fibers(wood or pulp particles).

In cases where the fiber roofing mat is comprised of a polysiloxane itcan be modified with various substituents which include linear,branched, or aromatic end-groups. Such end groups can optionally containoxygen, sulfur and/or nitrogen. Generally, the polysiloxanes areclassified as polyalkyl-silanes, polyaryl-silanes,polyalkylaryl-silanes, and polyether-siloxanes. The polysiloxanes thatare typically the most useful have a weight average molecular weight(MW) of at least 600. A preferred class of polysiloxanes ispolydialkylsiloxanes, with polydimethylsiloxane being highly preferred.

Some representative examples of suitable polysiloxanes that can beemployed in the fiber roofing mats employed in making the asphaltroofing shingles of this invention include, but are not limited to,polyalkylene oxide-modified polydimethylsiloxane-dimethylsiloxanecopolymer (MW=13,000); polyalkylene oxide-modifiedpolydimethylsiloxane-dimethylsiloxane copolymer (MW=3000); polyalkyleneoxide-modified polydimethylsiloxane-dimethylsiloxane copolymer(MW=4000); (carboxylatepropyl)methylsiloxane-dimethylsiloxane copolymer(MW>1000); dimethylsiloxane-(60% PO-40% EO) block copolymer (MW=20,000);(hydroxyalkyl functional) methylsiloxane-dimethylsiloxane copolymer(MW=5000); aminopropylmethylsiloxane-dimethylsiloxane copolymerMW=4500); aminoethylaminopropylmethoxysiloxane-dimethylsiloxanecopolymer (MW>1000); glycidoxy propyl dimethoxy silyl end-blockeddimethyl siloxane polymer (MW=5000); methacryloxy propyl dimethyoxysilyl dimethyl siloxane polymer (MW=40,000); vinyl dimethoxy silylend-blocked dimethyl siloxane polymer (MW=6500); aminoethylaminopropyldimethoxy silyl end-blocked dimethyl siloxane polymer (MW=3800);amine-alkyl modified methylalkylaryl silicone polymer (MW=7800); epoxyfunctional dimethylpolysiloxane copolymer (MW=8300);dimethylpolysiloxane (MW=26,439);dodecylmethylsiloxane-hydroxypolyalkyleneoxypropyl methylsiloxanecopolymer (MW=1900);(dodecylmethylsiloxane)-(2-phenylpropylmethylsiloxane) copolymer(MW>1000) and polyalkylene oxide-modifiedpolydimethylsiloxane-dimethylsiloxane copolymer (MW=600).

U.S. Pat. No. 6,737,369 discloses coated fiber roofing mats that can beutilized in the practice of this invention. These cured, non-wovenroofing mats are comprised of a mixture of fibers having different fiberlengths which are fixedly distributed in a binder, wherein the fiberscontain a polysiloxane compound. The mixture of fibers used in thesefiber mats contain from about 0 weight percent to about 100 weightpercent fibers having an average length of from about 0.5 mm to about 60mm and from about 0 weight percent to about 100 weight percent fibershaving an average length of from about 10 mm to about 150 mm. Morepreferably, from about 20 weight percent to about 80 weight percent ofthe fibers will have an average length of from about 10 mm to about 45mm and from about 20 weight percent to about 80 weight percent of fibershaving an average length of from about 30 mm to about 80 mm. The fibershaving differing fiber lengths typically have an average diameter offrom about 1 μm to about 100 μm, with an average diameter of from about5 μm to about 25 μm being more highly preferred. Such fibers can beobtained from commercial sources or made by techniques well known tothose skilled in the art. The binders that can be used in making suchfiber roofing mats are described in detail in U.S. Pat. No. 6,737,369and the teachings of U.S. Pat. No. 6,737,369 are incorporated herein byreference in their entirety.

Virtually any type of conventional roofing granules can be used inmaking the asphalt shingles of this invention. For instance, the roofinggranules can be comprised of greenstone, nephylene syenite, commongravel slate, gannister, quartzite, greystone, and the like. The roofinggranules used will typically be of a size that is within the range ofabout 420 micrometers to 1680 micrometers (40 mesh to 12 mesh). However,the use of larger or smaller granules is within the scope of thisinvention. For aesthetic purposes the roofing granules will typically becolored. In many cases two or more different colors of roofing granuleswill be mixed to attain the desired color for the roofing shingle.Colored roofing granules can be prepared by first preheating mineralrock granules having a size of about 420 micrometers to about 1680micrometers (40 to 12 US mesh) to a temperature which is within therange of 100° F. (38° C.) to 1000° F. (538° C.). Then, a paint slurrycontaining a pigment is applied to the heated granules in a mixer. Thecolor coated granules are subsequently heated in a kiln to a temperatureof about 350° F. (175° C.) to 1200° F. (650° C.). Then, the coloredgranules are cooled and passed to a post-treatment stage where thecolored granules are treated with an oil formulation in a rotary mixer.The oil formulation is applied to reduce dust and promote adhesion ofthe granules to the asphalt substrate. After the oil treatment, thegranules are removed from the post-treatment stage, transported, andsubsequently applied to the asphalt substrate. U.S. Pat. No. 5,286,544discloses a specific process for preparing colored roofing granules thatinvolves treating the granules with a composition that contains an oiland an elastomeric rubber that is compatible with the oil. The teachingof U.S. Pat. No. 5,286,544 are incorporated herein by reference withrespect to types of roofing granules that can be utilized in thepractice of this invention and with respect to techniques for makingsuch roofing granules.

U.S. Pat. No. 4,717,614 and U.S. Pat. No. 5,860,263 describe asphaltroofing shingles that can be made utilizing the improved industrialasphalt compositions of this invention as well as techniques formanufacturing such roofing shingles. The teachings of both U.S. Pat. No.4,717,614 and U.S. Pat. No. 5,860,263 are incorporated herein byreference in their entirety.

Asphalt roll roofing membranes can be made by coating a reinforcing maton both its upper surface and its lower surface with the improvedindustrial asphalt composition of this invention. The reinforcing matwill typically be a non-woven mat that is comprised of a polymericmaterial, such as polyester, which has the ability to stretch undertension. This is important so that the asphalt roll roofing will beflexible enough to withstand normal roof movement as well as expansionand contraction over the temperature range experienced in the geographicregion where the asphalt roll roofing is installed. Typically, theimproved industrial asphalt composition of this invention will alsocontain a polymeric modifier to provide the asphalt with an ability tostretch when used in such applications. The polymer modifier willtypically be a rubbery polymer and can optionally be a block copolymersuch as a styrene-butadiene-styrene block copolymer. The asphalt rollroofing will also preferably be coated on its upper surface with roofinggranules such as those that can be used in making roofing shingles.

Roofing underlayment can be made with the improved industrial asphalt ofthis invention by using such asphalt to saturate roofing paper or fibermat.

Built-up roofing can be made with the improved industrial asphalt ofthis invention by using such asphalt to adhere multiple layers ofroofing paper or felt together in manufacturing the built-up roofingmaterial. The built-up roofing will typically be covered on its uppersurface with roofing granules or gravel.

The improved industrial asphalt of this invention can also be used inmanufacturing asphalt based adhesive compositions and asphalt basedsealant compositions. This can be done by simply substituting theimproved industrial asphalt of this invention for the conventionalasphalts that are conventionally used in making asphalt based adhesivesand asphalt based sealant compositions. Such compositions will typicallyalso include one or more elastomeric materials, such as ground rubberfrom used tires. Such sealant and adhesive compositions can also containone or more synthetic rubbers, natural rubber, or an elastomeric blockcopolymer, such as a styrene-butadiene-styrene block copolymer.

This invention is illustrated by the following examples that are merelyfor the purpose of illustration and are not to be regarded as limitingthe scope of the invention or the manner in which it can be practiced.Unless specifically indicated otherwise, parts and percentages are givenby weight.

1. Durability Improvement

In this invention, asphalt durability (weathering resistance) is definedas the cycle-to-failure in a weather-o-meter according to ASTM D 4798-00“Standard Test Method for Accelerated Weathering Test Method Conditionsand Procedures for Bituminous Materials (Xeon-Arc Method)” Cycle A.Asphalt failure is determined according to ASTM D 1670.

COMPARATIVE EXAMPLE 1 AND WORKING EXAMPLE 2

The base asphalt 1 utilized in Comparative Example 1 was tested anddetermined to have a durability of 34 cycles. This asphalt was nottreated in accordance with the technique of this invention.

In Working Example 2 the same asphalt that was tested in ComparativeExample 1 (asphalt 1) was treated with mixing hydrated lime into it at atemperature of 300° F. (149° C.) with the mixing being conducted over aperiod of about 0.5 hours. The asphalt made by this procedure wassubsequently tested for durability and was determined to have adurability of 60 cycles. This experiment accordingly shows that thedurability of base asphalt can be improved by treating it with hydratedlime at an elevated temperature.

The results attained in this series of experiments at a Ca(OH)₂ level of0 weight percent and 2 weight percent are summarized in Table 1. TABLE 1Ca(OH)₂ Example Composition (weight %) Durability (cycles) 1 Asphalt 1 034 2 Lime Modified Asphalt 1 2 60

COMPARATIVE EXAMPLE 3 AND WORKING EXAMPLE 4

In this series of experiments a second base asphalt sample (asphalt 2)was treated in accordance with the method of this invention and comparedto a control. The base asphalt 2 tested in Comparative Example 3 wasdetermined to have a durability of 46 cycles. In Working Example 4hydrated lime was mixed into the base asphalt at a temperature of 300°F. (149° C.) over a period of 0.5 hours. The hydrated lime modifiedasphalt 2 prepared in Working Example 4 was determined to have adurability of 74 cycles. This experiment again shows that the durabilityof base asphalt can be improved by treating it with hydrated lime.

The results attained in this series of experiments at a Ca(OH)₂ level of0 weight percent and 2 weight percent are summarized in Table 2. TABLE 2Ca(OH)₂ Example Composition (weight %) Durability (cycles) 3 Asphalt 2 046 4 Lime Modified Asphalt 2 2 74

COMPARATIVE EXAMPLE 5 AND WORKING EXAMPLE 6

In this series of experiments a second base asphalt sample (asphalt 3)was treated in accordance with the method of this invention and comparedto a control. The base asphalt 3 tested in Comparative Example 5 wasdetermined to have a durability of 46 cycles. In Working Example 6hydrated lime was mixed into the base asphalt at a temperature of 300°F. (149° C.) over a period of 0.5 hours. The hydrated lime modifiedasphalt 3 prepared in Working Example 6 was determined to have adurability of 74 cycles. This experiment again shows that the durabilityof base asphalt can be improved by treating it with hydrated lime.

The results attained in this series of experiments at a Ca(OH)₂ level of0 weight percent and 2 weight percent are summarized in Table 3. TABLE 3Ca(OH)₂ Example Composition (weight %) Durability (cycles) 5 Asphalt 3 046 6 Lime Modified Asphalt 3 2 742. Low Temperature Flexibility Improvement

EXAMPLE 7

In this experiment the asphalt samples of Comparative Example 5 andWorking Example 6 were evaluated to determine their low temperatureflexibility. Modulus data was obtained from a dynamic mechanic analyzer(DMA) at different temperatures. At a fixed temperature, as the modulusof the asphalt increases its stiffness also increases and itsflexibility decreases. In other words, lower modulus is indicative ofbetter flexibility. In Working Example 6 where the asphalt 3 wasmodified with 2% hydrated lime (based on the asphalt weight), there issignificant drop in modulus, meaning the modified asphalt had betterflexibility at low temperature than did the control asphalt. Forexample, at −20° C., asphalt 3 had a modulus of 852.8 MPa, and themodified asphalt 3 has a modulus of 634.2 MPa, which shows a reductionof 218.6 MPa in modulus. In other words, the lime modified asphalt 3exhibited a better resistance to “low temperature thermal cracking” thanthe control asphalt.

The modulus of the control and the lime modified asphalt over a range ofdifferent temperatures is reported in Table 4. TABLE 4 Modulus (MPa)Asphalt 3 + Modulus reduction Temperature (° C.) Asphalt 3 2% Ca(OH)₂(MPa) −40 1056 931.3 124.7 −30 1019 837.9 181.1 −20 852.8 634.2 218.6−10 565.1 397.4 167.7 0 328 231.9 96.1 10 175.7 119.6 56.1 20 90.8260.35 30.5 30 45.36 28.48 16.93. Oxidative Hardening Resistance Improvement

EXAMPLE 8

In this experiment a lime modified asphalt composition was made andcompared to a control that was not modified with lime. In thisprocedure, 2 weight percent hydrated lime was mixed into asphalt 4 inthe working example. The control asphalt (asphalt 4) and the 2% hydratedlime modified asphalt 4 were subjected to weathering in aweather-o-meter for 10 days according to ASTM D 4798-00 “Standard TestMethod for Accelerated Weathering Test Method Conditions and Proceduresfor Bituminous Materials (Xeon-Arc Method)” Cycle A. The results of thisexperiment are reported in Table 5. TABLE 5 Angular frequency Agingindex (radian/sec) Asphalt 4 Asphalt 4 + 2% Ca(OH)₂ 0.6283 40.6 25.51.354 36.0 23.8 2.914 28.0 20.3 6.283 23.6 19.1 13.52 19.7 17.0 29.1116.8 14.6 62.46 14.4 12.9 134.7 12.2 11.3 292.4 10.2 9.5 434.4 9.7 9.1

Aging index was defined as the ratio of modulus of weather-o-meter agedasphalt to modulus of unaged asphalt:Aging index=modulus of weather-o-meter aged asphalt/modulus of unagedasphalt

Modulus was measured on a dynamic shear rheometer (DSR) at 76° C. atdifferent angular frequencies.

Data indicates that there is a significant drop in aging index withhydrated lime modification especially at low angular frequency, meaningthe addition of hydrated lime into asphalt can significantly reduce therate of asphalt aging or oxidation. In other words, an addition of asmall amount of hydrated lime, into asphalt can dramatically increaseasphalt's resistance to “oxidative hardening cracking”.

While certain representative embodiments and details have been shown forthe purpose of illustrating the subject invention, it will be apparentto those skilled in this art that various changes and modifications canbe made therein without departing from the scope of the subjectinvention.

1. A method for preparing an industrial asphalt comprising (1) heating abase asphalt to a temperature which is within the range of about 100° F.to 400° F. to produce a hot base asphalt, and (2) mixing from 0.1 weightpercent to 5 weight percent lime throughout the hot base asphalt whilethe mixture of hot base asphalt and lime is maintained at a temperaturewhich is within the range of 100° F. to 400° F. to produce theindustrial asphalt.
 2. A method as specified in claim 1 wherein the limeis in the form of solid particles or a solid powder.
 3. A method asspecified in claim 1 wherein the lime is added to the asphalt as anaqueous slurry.
 4. A method as specified in claim 1 wherein the mixingin step (2) is fulfilled by mechanical agitation.
 5. A method asspecified in claim 1 wherein the mixing in step (2) is fulfilled bybubbling an inert gas through the hot lime modified base asphalt.
 6. Amethod as specified in claim 1 wherein the lime is mixed into theasphalt in step (2) for a period of time which is within the range ofabout 10 minutes to about 4 hours.
 7. A method as specified in claim 1wherein the amount of lime added to the hot base asphalt in step (2) iswithin the range of 0.5 weight percent to 2 weight percent.
 8. A methodfor preparing an industrial asphalt comprising (1) heating a baseasphalt to a temperature which is within the range of about 100° F. to400° F. to produce a hot base asphalt, (2) adding from about 0.1 weightpercent to about 5 weight percent of a lime compound to the hot baseasphalt, (3) mixing the lime compound throughout the hot base asphalt toprepare a lime compound containing base asphalt, (4) heating the limecompound containing base asphalt to a temperature which is within therange of about 400° F. to about 550° F. to produce a hot lime compoundcontaining base asphalt, (5) sparging an oxygen containing gas throughthe hot lime compound containing base asphalt for a period of time whichis sufficient to produce the industrial asphalt.
 9. An industrialasphalt composition comprising asphalt and from 0.1 weight percent to 5weight percent lime.
 10. An industrial asphalt composition as specifiedin claim 9 wherein the lime is present in the asphalt composition at alevel which is within the range of 0.5 weight percent to about 2 weightpercent.
 11. An industrial asphalt composition as specified in claim 9wherein the asphalt has a softening point which is within the range of185° F. to 250° F., and wherein the asphalt has a penetration value ofat least 15 dmm.
 12. An industrial asphalt composition as specified inclaim 9 wherein the industrial asphalt has a softening point which iswithin the range of 185° F. to 235° F. and wherein the industrialasphalt has a penetration value which is within the range of 15 dmm to35 dmm.
 13. An industrial asphalt composition as specified in claim 9wherein the industrial asphalt has a softening point which is within therange of 190° F. to 220° F. and wherein the industrial asphalt has apenetration value which is within the range of 15 dmm to 25 dmm.
 14. Anindustrial asphalt as specified in claim 9 wherein the industrialasphalt is a Type I asphalt which has a softening point of from 135° F.to 151° F. and a penetration of from 18 dmm to 60 dmm at 77° F.
 15. Anindustrial asphalt as specified in claim 9 wherein the industrialasphalt is a Type II asphalt which has a softening point of from 158° F.to 176° F. and a penetration of from 18 dmm to 40 dmm at 77° F.
 16. Anindustrial asphalt as specified in claim 9 wherein the industrialasphalt is a Type III asphalt which has a softening point of from 185°F. to 205° F. and a penetration of from 15 dmm to 35 dmm at 77° F. 17.An industrial asphalt as specified in claim 9 wherein the industrialasphalt is a Type IV asphalt which has a softening point of from 210° F.to 225° F. and a penetration of from 12 dmm to 25 dmm at 77° F.
 18. Anindustrial asphalt composition as specified in claim 9 wherein the limeis hydrated lime.
 19. An industrial asphalt as specified in claim 9wherein the lime compound is dolomitic normal hydrate.
 20. An industrialasphalt as specified in claim 9 wherein the lime is a dolomitic pressurehydrate.
 21. An industrial asphalt as specified in claim 9 wherein thelime is quicklime.
 22. An industrial asphalt as specified in claim 9wherein the lime compound is a dolomitic quicklime.
 23. An asphaltroofing shingle having an upper surface and an underside, said asphaltroofing shingle being comprised of a fiber mat which is coated with anasphalt composition, wherein the upper surface of the asphalt roofingshingle includes a layer of roofing granules, wherein the asphaltcomposition has a softening point which is within the range of 185° F.to 250° F. and a penetration value of at least 15 dmm, and wherein theasphalt composition contains from 0.1 weight percent to 5 weight percentlime.
 24. An asphalt roofing shingle as specified in claim 23 whereinthe industrial asphalt has a softening point which is within the rangeof 185° F. to 235° F., and wherein the industrial asphalt has apenetration value which is within the range of 15 dmm to 35 dmm.
 25. Anasphalt roofing shingle as specified in claim 23 wherein the industrialasphalt has a softening point which is within the range of 190° F. to220° F., and wherein the industrial asphalt has a penetration valuewhich is within the range of 15 dmm to 25 dmm.
 26. An asphalt roofingshingle as specified in claim 23 wherein the lime is present in theasphalt composition at a level which is within the range of 0.5 weightpercent to about 2 weight percent.
 27. An asphalt roofing shingle asspecified in claim 23 wherein the lime is hydrated lime.
 28. An asphaltroofing shingle as specified in claim 23 wherein the fiber mat iscomprised of glass fibers.
 29. An asphalt roofing shingle as specifiedin claim 23 wherein the fiber mat is comprised of at least one polymericfiber selected from the group consisting of polyethylene fibers,polypropylene fibers, polyester fibers, nylon fibers, and acrylicfibers.
 30. An asphalt roofing shingle as specified in claim 23 whereinthe lime is dolomitic normal hydrate.
 31. An asphalt roofing shingle asspecified in claim 23 wherein the lime is dolomitic pressure hydrate.32. An asphalt roofing shingle as specified in claim 23 wherein the limeis quicklime.
 33. An asphalt roofing shingle as specified in claim 23wherein the lime is dolomitic quicklime.
 34. An asphalt roll roofingmembrane that is comprised of a reinforcing mat having an upper side anda lower side wherein said reinforcing mat is coated on its upper surfaceand its lower surface with an asphalt composition that is comprised ofasphalt and from 0.1 weight percent to 5 weight percent lime.
 35. Aroofing underlayment which is comprised of an asphalt saturated feltwherein the asphalt contains from 0.1 weight percent to 5 weight percentlime.
 36. A built-up roofing which is comprised of multiple layers ofroofing paper or felt that are adhered together with asphalt and whichis covered on its upper surface with mineral roofing granules or gravelwherein the asphalt contains from 0.1 to 5 weight percent lime.
 37. Anadhesive composition which is comprised of asphalt and of a polymermodifier wherein the asphalt contains from 0.1 to 5 weight percent lime.